This investigation studied the effects of Abamectin on the growth and some physiological activities of Chlorella vulgaris. The results showed that growth parameters decreased with increase in Abamectin concentrations. All the applied treatments of Abamectin strongly reduced the total sugars contents, total protein and total amino acids of Chlorella vulgaris.  The drop was more prominent and highly significant at higher dose. The data also showed that Abamectin treatment suppressed the activity of acid phosphatase, alkaline phosphatase, GOT and GPT of Chlorella vulgaris.